144 0001933694 XXXXXXXX LIVE 0001158324 COGENT COMMUNICATIONS HOLDINGS, INC. 000-51829 2450 N STREET, NW WASHINGTON DC 20037 2022954200 Howard Eve N Director Common CITIGROUP GLOBAL MARKETS INC.

388 Greenwich Street New York NY 10013

1626 133357.55 49024304 11/11/2024 NASDAQ Common CITIGROUP GLOBAL MARKETS INC.

CITIGROUP GLOBAL MARKETS INC. 388 Greenwich Street New York NY 10013

1709 140164.83 49024304 11/11/2024 NASDAQ Common CITIGROUP GLOBAL MARKETS INC.

CITIGROUP GLOBAL MARKETS INC. 388 Greenwich Street New York NY 10013

165 13532.59 49024304 11/11/2024 NASDAQ Common 10/06/2022 Compensation for Board Services Issuer N 1626 10/06/2022 Compensation for Board Services Common 01/04/2023 Compensation for Board Services Issuer N 1709 01/04/2023 Compensation for Board Services Common 04/05/2023 Compensation for Board Services Issuer N 165 04/05/2023 Compensation for Board Services Y 11/14/2024 /s/ Aegis J. Frumento as a duly authorized representative of Citigroup Global Markets Inc., as attorney-in-fact for the named Filer